The CaSiO_3:(Pb+Mn) Phosphor

Abstract

A calcium silicate phosphor, activated by lead and manganese, is described, and the conditions for its preparation are presented in detail. Under excitation by a low pressure mercury discharge, such as is employed in fluorescent lamps, this phosphor luminesces with an emission lying principally in the red end of the spectrum and with a high efficiency comparable to that of zinc beryllium silicate of the same luminescence color. Data are presented on the spectral emission of CaSiO3:Pb, CaSiO3:Mn, and CaSiO3:(Pb+Mn), both under cathode-ray and under 2537A excitation. It is shown that CaSiO3:Mn is excited to luminescence in the red end of the spectrum by cathode rays but not by ultraviolet light. The introduction of lead as an auxiliary impurity makes possible the excitation of this material by radiation in the neighborhood of the mercury resonance line. Qualitative absorption experiments indicate that the lack of response of CaSiO3:Mn to 2537A excitation is due to the absence of an absorption for this radiation; and that lead acts as a sensitizer for the manganese by introducing an absorption band in the vicinity of 2537A. The presence of a sensitizer is unnecessary under cathode-ray excitation, since in this case the energy is absorbed by the host crystal itself.

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